Nagios is a monitoring tool that can be used to monitor your infrastructure. It will alert you to when there are problems with services that are specified by use defined rules. One can download the Nagios Web gui, which resides in the share folder of the installation. You will need to point your apache config to that directory and ensure that cgi is enabled. It is also a good idea to password protect the installation since you can enable, disable, or schedule checks of your services. The Nagios Web GUI is easy to use and gives you easy control over even a complex infrastructure. Be sure to restart the apache web service after integrating the nagios configurations.